The invention relates to a circuit for controlling at least one electromnechanically activated inlet valve and at least one electromechanically activated outlet valve of an internal combustion engine.
Internal combustion engines whose charge cycle valves are activated electromechanically are known. In contrast to camshaft-activated valves, these valves are actuated so as to open and close as a function of the rotational position of the crankshaft; there is no fixed mechanically coupling to the crankshaft. Inlet electromechanical controlling elements which are charge cycle valves are known, for example, from German Patent DE 297 12 502 U1 and Published, European Patent Application EP 0 724 067 A1. They have a position of rest, which is located between a closed position and an opened position and after which they can be deflected by electromagnets.
In order to open or close a valve, the respective winding is energized, the necessary current being greater in a capture phase than in a holding phase in which the valve is held in an end position.
If the respective electromagnet is simply provided with current, a valve plate impacts on the valve seat at a high speed, which generates noise and promotes wear. In order to avoid this, the impact speed should be reduced. Mechanical stop damping has been investigated in this regard.
However, the energization is advantageously regulated in a suitable way, which, however, requires a relatively complex control algorithm because the control has to take place in real time. For example, the time period available for controlling the impact speed is only a few milliseconds.
Whereas in conventional camshaft-actuated valve drive the control times are not predefined in the operational control unit of the internal combustion engine, it is necessary to calculate and predefine appropriate control times in electromechanically activated valves.
It is accordingly an object of the invention to provide a circuit for controlling at least one electromechanically activated inlet valve and at least one electromechanically activated outlet valve of an internal combustion engine which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which permits the charge cycle valves to be activated in accordance with values predefined by the operational control unit of the internal combustion engine with the impact speed controlled in real time.
With the foregoing and other objects in view there is provided, in accordance with the invention, a circuit for controlling valves, including at least one electromechanically activated inlet valve and at least one electromechanically activated outlet valve, of a cylinder of an internal combustion engine. The circuit contains at least one placement control element having a plurality of output stages connected to electromagnets of the valves. At least one of the output stages is connected to each of the electromagnets of the valves. The placement control element receives timing signals and valve position signals. The placement control element actuates the output stages in dependence on the timing signals and, while processing the valve position signals for indicating a position of the valves, the placement control element regulates an energization of the electromagnets to bring about a gentle, low-noise placement of each of the valves to an end position. A digitally operating communications computer for evaluating a crankshaft position signal is connected to the placement control element. A communications connection connects the communications computer to an operational control unit of the internal combustion At engine. The communications computer exchanges data over the communications connection to the operational control unit and generates the timing signals received by the placement control element in dependence on the crankshaft position signal and of the data received from the operational control unit.
The invention is based on the fact that the control of the impact speed is to be separated from the communication with the operational control unit and from the generation of the timing signal from the predefined values of the operational control unit.
Separate placement control elements which are each assigned to one or more electromechanical final controlling elements control the movement sequence of the final controlling elements and thus bring about a gentle, low-noise, i.e. damped placement of the respective charge cycle valve in the end position. The communications computer preferably carries out the communication with the operational control unit of the internal combustion engine via a CAN-BUS and generates the timing signals for the placement control elements from the crankshaft signal, which is also supplied and from the requirements of the operational control unit. The timing signals are each as a rule a digital signal in which the rising edge indicates an opening of the valve and a trailing edge indicates a closing of the valve. For the inlet and outlet valves of each cylinder, a separate timing signal is fed to the respective placement control element in a unidirectional communication. It is also optionally possible for a separate timing signal to be provided for each coil in order to obtain greater room for maneuver when activating the is coils.
Because the communications computer evaluates the crankshaft signal, performs the communication with the operational control unit of the internal combustion engine and generates the timing signals for the placement control elements as a function of the data obtained from the operational control unit, the placement control elements are kept free for the control application and the control is not interrupted by other (communications) functions. In addition, the functions of the placement control can be paralleled by using a plurality of placement control elements, as a result of which the timing becomes less critical for a control algorithm. As a result of the fact that a central communications and timing unit is provided with the communications computer, there is only one communications partner for the other control units and no incorrect synchronizations of the individual placement control elements, and consequently the electromechanically activated charge cycle valves, are possible. Because the placement control elements advantageously operate digitally and are additionally connected to the communications computer by a serial interface and signal via the interface the statuses of the electromechanically activated charge cycle valves to the communications computer, all the statuses are centrally known and available.
In the event of a placement control element failing, the communications computer can issue instructions to deactivate the other two valves of the cylinder, i.e. move them into the closed position. The internal combustion engine can then run in an emergency operating mode without the cylinder and without non-combusted fuel getting into the exhaust track or combustion gases getting into the intake track.
The provision of a plurality of placement control elements also permits all the processors, in particular the processor of the communications computer and that of the placement control elements, used in the circuit to monitor one another.
In one advantageous embodiment, the coils of the electromechanical charge cycle valves are actuated by the placement control elements via AND elements whose second input can be actuated with the timing signal which the communications computer supplies to the placement control element, and the actuation can take place if the placement control element has enabled this by a respective locking element. This has the advantage that the energization of a coil of the electromechanically activated valve is terminated simultaneously with a trailing edge of the respective timing signal. Any offset as a result of programming running times in the placement control element can thus be optionally eliminated.
In accordance with an added feature of the invention, the placement control element is one of a plurality of placement control elements and one of the placement control elements is coupled to the inlet valve and another of the placement control elements is coupled to the outlet valve.
In accordance with an additional feature of the invention, the placement control element has a processor; and a bidirectional communications interface connects the communications computer to the placement control element for exchanging further data.
In accordance with a further feature of the invention, each of the placement control elements detects a position of the valves and signals a malfunction of one of the valves to the communications computer.
In accordance with another feature of the invention, the communications-computer monitors at least one of a temperature of the output stages, a supply voltage of the output stages, a it supply voltage of position sensors used, and a supply voltage of all of the placement control elements.
In accordance with a further added feature of the invention, the communications computer is one of a plurality of communications computers. The inlet valve is one of a plurality of inlet valves and the outlet valve is one of a plurality of outlet valves, and one of the communications computers is provided for all of the inlet valves and another one of the communications computer is provided for all of the outlet valves.
In accordance with a further additional feature of the invention, a housing and an active cooling system connected to the housing are provided. The plurality of placement control elements are disposed with the output stages in the housing.
In accordance with another added feature of the invention, if a valve failure is indicated by one of the placement control elements, the communications computer brings about a deactivation of the other valves of the cylinder in question to a closed position.
In accordance with another additional feature of the invention, the electromagnets each have a winding resulting in a plurality of windings and a feedline connected to each of the windings resulting in a plurality of feedlines. A logic circuit is disposed in the feedlines, the logic circuit receives an associated timing signal so that the logic circuit brings about, directly by the associated timing signal, a direct shutting down of energization of an associated winding.
In accordance with a concomitant feature of the invention, a communications line connects the communications computer to the placement control element. The logic circuit has first AND elements. One of the first AND elements is connected in each of the feedlines to a respective winding and each of the first AND elements has an output connected to the respective winding, a first input connected to the placement control element and a second input. The logic circuit has a second AND element having a first input connected to the communications line, a second input connected to the placement control element, and an output connected to the second input of each of the first AND elements so that, when the second AND element is enabled by the placement control element, a respective one of the timing signals brings about a direct shutting down of the energization of the-respective winding.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as it embodied in a circuit for controlling at least one electromechanically activated inlet valve and at least one electromechanically activated outlet valve of an internal combustion engine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.